What Is Your Diagnosis?

Dennis Ting Wheat Ridge Veterinary Specialists, 3695 Kipling St, Wheat Ridge, CO 80033.

Search for other papers by Dennis Ting in
Current site
Google Scholar
PubMed
Close
 DVM
,
Steven W. Petersen Wheat Ridge Veterinary Specialists, 3695 Kipling St, Wheat Ridge, CO 80033.

Search for other papers by Steven W. Petersen in
Current site
Google Scholar
PubMed
Close
 DVM, DACVS
,
Elisa M. Mazzaferro Wheat Ridge Veterinary Specialists, 3695 Kipling St, Wheat Ridge, CO 80033.

Search for other papers by Elisa M. Mazzaferro in
Current site
Google Scholar
PubMed
Close
 DVM, PhD, DACVECC
,
Leila T. Worth Wheat Ridge Veterinary Specialists, 3695 Kipling St, Wheat Ridge, CO 80033.

Search for other papers by Leila T. Worth in
Current site
Google Scholar
PubMed
Close
 VMD, PhD, DACVR
, and
Steven W. Petersen Wheat Ridge Veterinary Specialists, 3695 Kipling St, Wheat Ridge, CO 80033.

Search for other papers by Steven W. Petersen in
Current site
Google Scholar
PubMed
Close
 DVM, DACVS

Click on author name to view affiliation information

History

A 6-year-old sexually intact male Labrador Retriever was referred for surgical evaluation after being hit by an automobile earlier the same day. The dog was initially treated by the referring veterinarian with lactated Ringer's solution (1 L, IV bolus) for cardiovascular support. The dog was also treated with morphine (0.7 mg/kg [0.32 mg/lb], IM) and diazepam (0.3 mg/kg [0.14 mg/lb], IV) for signs of pain and to provide sedation. Multiple pelvic fractures were detected on radiographs obtained by the referring veterinarian.

On physical examination, the dog was cardiovascularly stable with a normal sinus rhythm as determined by ECG. Blood pressure values were normal, and strong synchronous femoral pulses were detected. No respiratory abnormalities were detected. Orthopedic examination revealed crepitus and instability over the tuber sacral region and ischiatic tubers bilaterally. The entire right pelvic limb was severely swollen, with bruising on the lateral aspect of the limb and in the inguinal region. Extension of the right stifle joint with concurrent flexion of the right tarsocrural joint (plantigrade stance) was also identified. A stress leukogram was detected on CBC. Radiographs of the pelvis were obtained (Figure 1).

Figure 1—
Figure 1—

Lateral (A) and ventrodorsal (B) radiographic views of the pelvis of a 6-year-old sexually intact male Labrador Retriever referred for surgical evaluation after being hit by an automobile earlier the same day.

Citation: Journal of the American Veterinary Medical Association 228, 10; 10.2460/javma.228.10.1497

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page

Radiographic Findings and Interpretation

In addition to the multiple pelvic fractures (Figure 2), caudal, distal, and lateral displacement of the lateral fabella of the right pelvic limb is evident. This was likely caused by avulsion of the tendon of origin of the lateral head of the gastrocnemius muscle from its attachment on the femur.

Figure 2—
Figure 2—

Same ventrodorsal radiographic view as in Figure 1. Notice multiple pelvic fractures (black arrows) and the location of the lateral fabella (white arrow) of the right pelvic limb.

Citation: Journal of the American Veterinary Medical Association 228, 10; 10.2460/javma.228.10.1497

Comments

Radiography of the right stifle joint revealed that the cause for the plantigrade stance was avulsion of the origin of the lateral head of the gastrocnemius muscle (Figure 3). Surgical reduction and stabilization of the ilial body fractures was achieved with bone plates placed laterally and ventrally. The origin of the lateral head of the gastrocnemius muscle was reattached with a combination of cerclage wires and tissue anchors followed by immobilization of the tarsocrural joint in partial extension to minimize stress on the repair.

Figure 3—
Figure 3—

Lateral radiographic view of the right stifle joint of the dog in Figure 1. Notice that the location of the lateral fabella (white arrow) is compatible with avulsion of the tendon of origin of the lateral head of the gastrocnemius muscle.

Citation: Journal of the American Veterinary Medical Association 228, 10; 10.2460/javma.228.10.1497

The gastrocnemius muscle consists of 2 heads originating from the lateral and medial supracondylar tuberosities of the femur.1 Each tendon of origin contains a prominent sesamoid bone known as the lateral and the medial fabellae. The 2 heads of the gastrocnemius muscle fuse with each other to form a broad tendon that tapers distally and inserts on the tuber calcanei. The gastrocnemius muscle and tendon are the main components of the Achilles mechanism. Because of the anatomic constraints associated with points of origin and insertion, concurrent extension of the stifle joint and flexion of the tarsocrural joint is not possible with an intact Achilles mechanism. Common differential diagnoses for abnormal plantigrade stance include sciatic nerve injury, partial or complete rupture of the Achilles mechanism, and fracture of the tuber or the shaft of the calcaneus. In the dog reported here, physical examination and radiographic findings resulted in a diagnosis of avulsion of the origin of the lateral head of the gastrocnemius muscle.

Avulsion of the origin of the gastrocnemius muscle is rare in dogs, and only a few cases have been reported. Avulsion of the origin of the gastrocnemius muscle is usually associated with trauma, affecting either the lateral or medial heads of the muscle,2–4 although atraumatic avulsion of both origins of the gastrocnemius muscle due to a chronic pathologic lesion has been reported.5 Radiography was an integral part of the diagnostic workup in all reported cases and revealed displacement of either or both fabellae. All but one of those cases was treated surgically. Reported surgical options for avulsion of the origin of the gastrocnemius muscle include direct wire reattachment,4 figure-of-eight wire via bone tunnel,5 and spiked washer and screw.3 One small-breed dog was conservatively treated with exercise restriction followed by physical therapy.2 In all cases, the outcome was generally favorable; however, the recovery period ranged from 2 to 4 months before the limb regained satisfactory use.5 Because of the severe pelvic trauma in addition to the gastrocnemius avulsion, the dog reported here received appropriate physical therapy after surgery and gradually regained mobility of the affected limb.

  • 1

    Hermanson JW, Evans HE. Muscles of the pelvic limb. In: Miller's anatomy of the dog. 3rd ed. Philadelphia: WB Saunders Co, 1993;369370.

    • Search Google Scholar
    • Export Citation
  • 2

    Muir P, Dueland RT. Avulsion of the origin of the medial head of the gastrocnemius muscle in a dog. Vet Rec 1994;135:359360.

  • 3

    Prior JE. Avulsion of the lateral head of the gastrocnemius muscle in a working dog. Vet Rec 1994;134:382383.

  • 4

    Chaffee VW, Knecht CD. Avulsion of the medial head of the gastrocnemius in the dog. Vet Med Small Anim Clin 1975;70:929931.

  • 5

    Robinson A. Atraumatic bilateral avulsion of the origins of the gastrocnemius muscle. J Small Anim Pract 1999;40:498500.

All Time Past Year Past 30 Days
Abstract Views 112 0 0
Full Text Views 881 797 155
PDF Downloads 323 234 19
Advertisement